Sedimentary Controls on Fracture Formation in Grainy and Muddy Slope Deposits (Permian), West Texas

Variable depositional and diagenetic processes in carbonate slope environments and rock strength/composition strongly influence the stacking of mechanical stratigraphic units, which may control fracture length, height, aperture, spacing, and geometry in post-depositional settings. Outcrop studies are essential for characterizing fractured carbonate systems, as they provide the most comprehensive understanding of how vertical and lateral facies variability and associated diagenetic events affect fracture network geometry at multiple scales. The Pinery and Lamar Members of the Permian-aged Bell Canyon Formation, located on the foreslope of the Capitan Reef system in the Guadalupe Mountains of west Texas, exhibit the products of various carbonate slope depositional processes and resultant geometries that are well-exposed for complementary fracture studies. While published studies have linked burial diagenesis to fracture network enhancement, the original depositional controls on burial-fracture-network development remain poorly constrained. The goal of this outcrop work is to constrain the mechanical stratigraphy along depositional strike and dip, focusing on differences between grain-rich facies in the Pinery Member, and mud-rich facies in the Lamar Member, in multiple canyons along the Guadalupe Mountains front, to address the following questions: 1) What are the original sedimentary controls on fracture initiation, propagation and termination in terms of products of depositional processes, composition, grain size, bed thickness, and carbonate rock texture?, 2) What fracture types are observed in mid- to lower slope debris aprons, and can we determine their timing (syndepositional, burial, tectonic)?, 3) Are there predictive relationships between fracture aspect ratios and slope processes/resultant geometries/sediment composition?